A pioneering new study has warned that the potential hidden economic cost to property from groundwater flooding in England could be as much as £530 million per year.

The study by environmental consutancy ESI has examined national mapping and developed preliminary economic analysis on the risk of groundwater flooding to property and infrastructure.National mapping shows significant risk from groundwater as part of overall flood risk.

This, combined with other flood risks has now created the first “Flooding from All Sources” dataset using advanced modelling techniques on a 5m grid.

Drawing on available Environment Agency, Ordnance Survey, and British Geological Survey data and the GeoSmart national groundwater flood risk maps, ESI are discussing with Defra how these ‘flood risk from all sources’ maps may be made available for public use.

Launching the mapping and risk analysis, ESI is calling for an immediate increase in the Environment Agency’s flood risk management function, with more focus on groundwater science on a catchment basis.

ESI believes that flood risk analysis and recommendations from recent government reviews have, to date, been too “rivers-centric” and a more robust risk management plan is needed. This must be developed to understand and tackle a costly, but largely ignored natural hazard.

ESI Director Mark Fermor commented:

“Groundwater is poorly understood. We know to our cost that the general public, businesses and authorities cannot foresee what is going on beneath our feet.  Our national modelling has revealed the scale of the problem but also highlights very large uncertainties, partly due to lack of catchment-based focus and the role of groundwater.”

“Our regulatory structure is not looking at the issues from a catchment flow perspective. Groundwater is classed as ‘Local Flooding’ and part of ‘Surface Water Flooding’, assigning risk management to local authorities within administrative rather than catchment boundaries”

“This is a serious barrier to a clear and objective understanding of the risk. Most of the water in our southern English rivers is derived from groundwater, so it is obvious that a catchment approach is essential.”

“Local Authority boundaries and river catchments do not match up, “continued Fermor, “so it is unfair to expect a Council or Unitary Authority to be able to assess flood risk effectively.

“We should empower the Environment Agency, our catchment specialists, to take on this role, and provide updated risk management plans as a matter of urgency before we are faced with another difficult winter. Without detailed groundwater flood risk mapping at present, they cannot make vital strategic planning decisions.”

Many insurance policies exclude groundwater flood risk

ESI has also warned that many insurance policies exclude groundwater. The consultancy believes that clearer recognition of the risk to property and the role that groundwater plays in driving catchment flood risk will help the householder and the insurance industry wake up to the need for appropriate cover.

Mark Fermor concluded:

“Homeowners and businesses remain vulnerable and face potentially £500m+ worth of economic loss to property every year, according to our preliminary analysis.  Infrastructure impact and consequential losses add to this.  Groundwater flood risk maps are now available, which for the first time enable a joined up approach to understanding threats to property and infrastructure from flooding from all sources.”

Click here to download a Technical Summary on the preliminary economic impact of groundwater flood risk.

Waterbriefing is media partner with the Environment Agency’s major three-day conference and exhibition Flood and Coast 2017 which takes place from 28 to 30 March 2017 in Telford. Click here for more information